The highly stressed and wear-resistant parts of ball and roller bearings, gear transmissions, etc., which are subjected to rolling fatigue must be hardened. A steel with approximately 1 wt. % of carbon, i.e., a so-called roller bearing steel (e.g., 100 Cr 6), is usually used for these parts. It is usually heated to a temperature above 1,100.degree. C., shaped into tubes or bars, cooled, given an intermediate annealing, soft-machined, hardened, and then finish-ground.
In the production of parts of roller bearing steel (100 Cr 6), therefore, it is necessary to conduct an expensive soft annealing process between the shaping and the other operations to ensure that mechanical processing can be carried out easily and that the parts can be hardened readily. It is also known that rings of roller bearing steel can be subjected to thermo-mechanical treatments. These are processes in which shaping and a heat treatment are combined effectively with each other. These processes make it possible to harden the parts from the heat of working, so that specific material properties can be improved and/or so that the heat treatment part of the process can substitute for another, i.e. separate heat treatment. In particular, the otherwise conventional soft annealing can be omitted, which means that the amount of energy required is reduced (see, for example, the German journal Stahl und Eisen, Vol. 108, No. 12, pp. 595-603, 1988).
In these known processes, the rings are first rolled and then quenched via A.sub.1 from the heat of working. They are then annealed (hardened and tempered) and hard-machined. In most cases, however, a soaking furnace must be placed after the working operation to achieve a higher degree of process reliability and uniformity. Quenching usually takes place in a brine or oil bath. The distortions which thus occur, however, must always be corrected by expensive hard machining.